The present invention relates to a method and apparatus for applying a reclosable fastener strip to the continuous web of film on a form, fill and seal machine. There are two manufacturing methods for forming reclosable packages on form, fill and seal machines. In one method, the reclosable fastener strip extends parallel to the feed direction of the continuous web of film. In the second method, the reclosable fastener strip extends transverse to the feed direction of the continuous web of film. The present invention relates to the method in which the reclosable fastener strip extends transverse to the feed direction of the continuous web of film. It is important in forming reclosable packages using this method that the timing of the cross sealing jaws be coordinated with the position at which the reclosable fastener strip was bonded to the continuous web of film. U.S. Pat. No. 4,655,862 discloses a mechanism for cutting, locating and securing a flexible plastic reclosable fastener strip across the longitudinal axis of the continuous web of film that is being used to create a package having a reclosable top.
U.S. Pat. No. 4,909,017 discloses a machine for making bags that have a reclosable fastener on a form, fill and seal machine. The bag forming process disclosed in this patent includes the step of securing a reclosable fastener strip to the film such that it extends transverse to the direction of film feed. In both U.S. Pat. Nos. 4,655,862 and 4,909,017, a continuous web of film is fed to the form, fill and seal machine from a film roll. Prior to reaching the form, fill and seal machine, a reclosable fastener strip is attached to the surface of the continuous web of film. The reclosable fastener strips are cut from a continuous ribbon of reclosable fastener material that is provided from a supply roll. The strip is guided to the lateral edge of the continuous web of film and then into a channel member that overlays the film. The use of a conventional cutting element as suggested in these patents has the disadvantage that the knife blades dull quickly when used on machines that produce upward of a hundred packages per minute. Also, conventional cutting knives get contaminated with melted plastic as a result of heat generated by the rapid cutting action. The use of conventional cutting knives produce a service problem for machines of this type. A reclosable fastener strip is cut from the continuous ribbon which is then positioned by the channel on the upper surface of the continuous web of film. The lower surface of the reclosable fastener strip is secured to the upper surface of the continuous web of film. These patents disclose systems that require a separate apparatus outside of the form, fill and seal machine for securing the reclosable fastener strip to the film. As a result, there is a long span of film extending from the location outside the form, fill and seal machine where the reclosable fastener strip was bonded to the film to the point where the continuous web of film encounters the forming shoulder.
The continuous web of film from which packages are manufactured is very thin and is difficult to control. For this reason, it is desirable to mount the separate device for bonding the reclosable fastener strip to the continuous web of film close to the form, fill and seal machine that they serve. In fact, they are mounted so close that they may interfere with the normal servicing of the form, fill and seal machine. The long span of continuous film utilized by these machines must be processed and coordinated to assure that the reclosable fastener strip is properly located with respect to where the cross seal of the bag is formed and to assure that it is not damaged as it is moved from the point where it is secured to the continuous web of film to the point where it encounters the forming shoulder.
In addition, these prior art machines must complete the feeding, severing to length and bonding of the segment of reclosable fastener strip to the film before this sequence for the next segment can begin. Thus, the speed of the form, fill and seal machine that has been retrofitted with the prior art machines disclosed in these prior art patents is very limited. Also, in the prior art machines, the two halves of the reclosable fastener strip are not positively interconnected and, thus, could separate from each other or shift relative to each other during the subsequent package forming procedure.